Impermeable flexible bags are used abundantly in the pharmaceutical industry and more particularly in the field of solutions for perfusions. Such bags are made on the basis of polymerized materials satisfying a very wide variety of conditions: impermeability to gases and vapors, transparency, inertness towards the substances they contain, i.e. essentially aqueous solutions of salts, carbohydrates, amino acids or other substances, heat stability so that they can withstand hot sterilization, weldability, and so on. The material most widely used in this field is polyvinyl chloride (PVC), which satisfies the most important of the conditions mentioned above; however PVC is a source of pollution because it releases chlorinated substances on combustion, which is no longer permissible. Furthermore, the stability of PVC is not absolute, especially towards certain solutions.
For reasons primarily concerning protection of the environment, industry is therefore faced with the need to find materials to replace PVC, preferably simple or composite polymerized materials combining all the qualities inherent in PVC, without at the same time being a source of pollution. The object of the invention is precisely to propose a novel polymerized material which makes it possible advantageously to solve the problem presented by the replacement of PVC, especially in the field of impermeable flexible bags for sterile solutions.
It is in fact very rare to find a simple polymerized material (homopolymer or copolymer) which by itself possesses all the requisite characteristics and which is commercially attractive as well. Research has therefore been directed towards the production of composite, so-called multilayer materials in which one endeavors to combine the intrinsic properties of each constituent in order to achieve the desired result. This is not an easy task because there are a number of conditions to satisfy (weldability, stability, flexibility, impermeability, etc.); furthermore, said constituents must be mutually compatible. The multilayer material as defined in claim 1 satisfies all these conditions.